Save JSON to File in Python

Working with JSON files is a common task in Python programming. In this guide, we'll explore different methods to save JSON data to files efficiently and properly.

Using json.dump() Method

The simplest way to write JSON data to a file is using the json.dump() method. This method directly writes Python objects to a file in JSON format.

import json

data = {
    "name": "John Doe",
    "age": 30,
    "city": "New York"
}

with open('data.json', 'w') as file:
    json.dump(data, file)

Pretty Printing JSON

For better readability, you can format the JSON output using the indent parameter. This is particularly useful when debugging or creating human-readable files.

import json

data = {
    "name": "John Doe",
    "age": 30,
    "city": "New York"
}

with open('formatted_data.json', 'w') as file:
    json.dump(data, file, indent=4)

{
    "name": "John Doe",
    "age": 30,
    "city": "New York"
}

Using json.dumps() for String Conversion

Sometimes you might need to convert your data to a JSON string first using json.dumps() before writing it to a file. For more details, check out our Python JSON to String Conversion Guide.

import json

data = {"name": "John Doe", "age": 30}
json_string = json.dumps(data, indent=4)

with open('string_data.json', 'w') as file:
    file.write(json_string)

Handling Special Characters

When dealing with special characters or non-ASCII text, you can use the ensure_ascii parameter to properly handle Unicode characters.

import json

data = {
    "name": "José",
    "city": "São Paulo"
}

with open('unicode_data.json', 'w', encoding='utf-8') as file:
    json.dump(data, file, ensure_ascii=False, indent=4)

Appending to JSON Files

If you need to add more data to an existing JSON file, you'll need to read the file first, modify the data, and write it back. Learn more in our guide about how to append objects to JSON in Python.

Error Handling

Always implement proper error handling when working with files to manage potential issues like permission errors or invalid JSON data.

import json

try:
    with open('data.json', 'w') as file:
        json.dump(data, file)
except IOError as e:
    print(f"Error writing to file: {e}")
except json.JSONDecodeError as e:
    print(f"Error encoding JSON: {e}")

Conclusion

Saving JSON to files in Python is straightforward using the built-in json module. For more advanced operations, check out our guides on Python JSON Dump and Pretty Print JSON.